Luminescence device, display apparatus and metal coordination compound

ABSTRACT

A luminescence device comprising a pair of electrodes and an organic compound layer disposed between the electrodes. The layer contains a metal coordination compound represented by the following formula (1):                  
         wherein M is Ir, Rh or Pd; n is 2 or 3; and X 1  to X 8  is, independently, a hydrogen atom or a substituent selected from the group consisting of a halogen atom; a nitro group; a trifluoromethyl group; a trialkylsilyl group having three linear or branched alkyl groups each independently having 1–8 carbon atoms; and a linear or branched alkyl group having 2–20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —C(O)—, —C(O)—O—, —O—C(O)—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom.

This application is a division of application Ser. No. 09/961,075, filedSep. 24, 2001, which is incorporated herein by reference.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to a luminescence device, a metalcoordination compound therefor and a display apparatus including theluminescence device. More specifically, the present invention relates toan organic (electro-)luminescence device employing a metal coordinationcompound having a formula (1) or (2) appearing hereinafter as aluminescence material, the metal coordination compound adapted for usein the luminescence device, and a display apparatus using theluminescence device.

An organic electroluminescence (EL) device has been extensively studiedas a luminescence device with a high responsiveness and high efficiency.

The organic EL device generally has a sectional structure as shown inFIG. 1A or 1B (e.g., as described in “Macromol. Symp.”, 125, pp. 1–48(1997)).

Referring to the figures, the EL device generally has a structureincluding a transparent substrate 15, a transparent electrode 14disposed on the transparent substrate 15, a metal electrode 11 disposedopposite to the transparent electrode 14, and a plurality of organic(compound) layers disposed between the transparent electrode 14 and themetal electrode 11.

Referring to FIG. 1, the EL device in this embodiment has two organiclayers including a luminescence layer 12 and a hole transport layer 13.

The transparent electrode 14 may be formed of a film of ITO (indium tinoxide) having a larger work function to ensure a good hole injectionperformance into the hole transport layer. On the other hand, the metalelectrode 11 may be formed of a layer of aluminum, magnesium, alloysthereof, etc., having a smaller work function to ensure a good electroninjection performance into the organic layer(s).

These (transparent and metal) electrodes 14 and 11 may be formed in athickness of 50–200 nm.

The luminescence layer 12 may be formed of, e.g., aluminum quinolinolcomplex (representative example thereof may include Alq3 describedhereinafter) having an electron transporting characteristic and aluminescent characteristic. The hole transport layer 13 may be formedof, e.g., triphenyldiamine derivative (representative example thereofmay include α-NPD described hereinafter) having an electron donatingcharacteristic.

The above-described EL device exhibits a rectification characteristic,so that when an electric field is applied between the metal electrode 11as a cathode and the transparent electrode 14 as an anode, electrons areinjected from the metal electrode 11 into the luminescence layer 12 andholes are injected from the transparent electrodes 14.

The thus-injected holes and electrons are recombined within theluminescence layer 12 to produce excitons, thus causing luminescence. Atthat time, the hole transport layer 13 functions as an electron-blockinglayer to increase a recombination efficiency at the boundary between theluminescence layer 12 and the hole transport layer 13, thus enhancing aluminescence efficiency.

Referring to FIG. 1B, in addition to the layers shown in FIG. 1A, anelectron transport layer 16 is disposed between the metal electrode 11and the luminescence layer 12, whereby an effective carrier blockingperformance can be ensured by separating functions of luminescence,electron transport and hole transport, thus allowing effectiveluminescence.

The electron transport layer 16 may be formed of, e.g., oxadiazolederivatives.

In ordinary organic EL devices, fluorescence caused during a transitionof luminescent center molecule from a singlet excited state to a groundstate is used as luminescence.

On the other hand, not the above fluorescence (luminescence) via singletexciton, phosphorescence (luminescence) via triplet exciton has beenstudied for use in organic EL device as described in, e.g., “Improvedenergy transfer in electrophosphorescent device” (D. F. O'Brien et al.,Applied Physics Letters, Vol. 74, No. 3, pp. 442–444 (1999)) and “Veryhigh-efficiency green organic light-emitting devices based onelectrophosphorescence” (M. A. Baldo et al., Applied Physics Letters,Vol. 75, No. 1, pp. 4–6 (1999)).

The EL devices shown in these documents may generally have a sectionalstructure shown in FIG. 1C.

Referring to FIG. 1C, four organic layers including a hole transferlayer 13, a luminescence layer 12, an exciton diffusion-prevention layer17, and an electron transport layer 16 are successively formed in thisorder on the transparent electrode (anode) 14.

In the above documents, higher efficiencies have been achieved by usingfour organic layers including a hole transport layer 13 of α-NPD (shownbelow), an electron transport layer 16 of Alq3 (shown below), an excitondiffusion-prevention layer 17 of BPC (shown below), and a luminescencelayer 12 of a mixture of CPB (shown below) as a host material withIr(ppy)₃ (shown below) or PtOEP (shown below) as a guest phosphorescencematerial doped into CBP at a concentration of ca. 6 wt. %.

-   -   Alq3: tris(8-hydroxyquinoline) aluminum (aluminum-quinolinol        complex),    -   α-NPD:        N4,N4′-di-naphthalene-1-yl-N4,N4′-diphenyl-biphenyl-4,4′-diamine        (4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl),    -   CBP: 4,4′-N,N′-dicarbazole-biphenyl,    -   BCP: 2,9-dimethyl-4,7-diphenyl-1,10-phenan-throline,    -   Ir(ppy)₃: fac tris(2-phenylpyridine)iridium        (iridium-phenylpyridine complex), and    -   PtEOP: 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum        (platinum-octaethyl porphine complex).

The phosphorescence (luminescence) material used in the luminescencelayer 12 has attracted-notice. This is because the phosphorescencematerial is expected to provide a higher luminescence efficiency inprinciple.

More specifically, in the case of the phosphorescence material, excitonsproduced by recombination of carriers comprise singlet excitons andtriplet excitons presented in a ratio of 1:3. For this reason, whenfluorescence caused during the transition from the singlet excited stateto the ground state is utilized, a resultant luminescence efficiency is25% (as upper limit) based on all the produced excitons in principle.

On the other hand, in the case of utilizing phosphorescence causedduring transition from the triplet excited state, a resultantluminescence efficiency is expected to be at least three times that ofthe case of fluorescence in principle. In addition thereto, ifintersystem crossing from the singlet excited state (higher energylevel) to the triplet excited state is taken into consideration, theluminescence efficiency of phosphorescence can be expected to be 100%(four times that of fluorescence) in principle.

The use of phosphorescence based on transition from the triplet excitedstate has also been proposed in, e.g., Japanese Laid-Open PatentApplication (JP-A) 11-329739, JP-A 11-256148 and JP-A 8-319482.

An iridium-phenylpyridine complex having a methyl substituent has beendescribed in “Preprint for the 61^(st) Academical Lecture of the AppliedPhysics Society of Japan”, the third volume, P. 1117, 6p-ZH-1 (2000)(“Document 1”). Further, an iridium-phenylpyridine complex having 4-,5-fluorine substituents (herein, referred to as a “metal coordinationcompound A” has been described in “Polymer Preprints”, 41(1), pp.770–771 (2000) (“Document 2”).

However, the above-mentioned organic EL devices utilizingphosphorescence have accompanied with a problem of luminescentdeterioration particularly in an energized state.

The reason for luminescent deterioration has not been clarified as yetbut may be attributable to such a phenomenon that the life of tripletexciton is generally longer than that of singlet exciton by at leastthree digits, so that molecule is placed in a higher-energy state for along period to cause reaction with ambient substance, formation ofexciplex or excimer, change in minute molecular structure, structuralchange of ambient substance, etc.

Accordingly, the (electro)phosphorescence EL device is expected toprovide a higher luminescence efficiency as described above, while theEL device is required to suppress or minimize the luminescentdeterioration in energized state.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a luminescence devicecapable of providing a high-efficiency luminescent state at a highbrightness (or luminance) for a long period while minimizing thedeterioration in luminescence in energized state.

Herein, although evaluation criteria for “high efficiency” and “highbrightness (luminance) for a long period” may vary depending onluminescent performances required for an objective luminescence device(EL device), for example, a luminescence efficiency of at least 1 cd/Wbased on an inputted current value may be evaluated as “highefficiency”. Further, a luminance half-life of, e.g., at least 500 hoursat the time of luminescence at an initial luminance of 100 cd/m² may beevaluated as “high brightness (luminance) for a long period” or asmaller luminance deterioration in energized state.

Another object of the present invention is to provide a metalcoordination compound as a material suitable for an organic layer forthe luminescence device.

According to the present invention, there is provided a luminescencedevice, comprising: an organic compound layer comprising a metalcoordination compound represented by the following formula (1):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independentlydenote hydrogen atom or a substituent selected from the group consistingof halogen atom; nitro group; trifluoromethyl group; trialkylsilyl grouphaving three linear or branched alkyl groups each independently having1–8 carbon atoms; and a linear or branched alkyl group having 2–20carbon atoms capable of including one or at least two non-neighboringmethylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—,—O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom whichcan be replaced with fluorine atom; with the proviso that at least oneof X1 to X8 is a substituent other than hydrogen atom, and X2 and X3cannot be fluorine atom at the same time.

According to the present invention, there is also provided a metalcoordination compound, adapted for use in a luminescence device,represented by the following formula (1):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independentlydenote hydrogen atom or a substituent selected from the group consistingof halogen atom; nitro group; trifluoromethyl group trialkylsilyl grouphaving three linear or branched alkyl groups each independently having1–8 carbon atoms; and a linear or branched alkyl group having 2–20carbon atoms capable of including one or at least two non-neighboringmethylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—,—O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom whichcan be replaced with fluorine atom; with the proviso that at least oneof X1 to X8 is a substituent other than hydrogen atom, and X2 and X3cannot be fluorine atom at the same time.

The present invention provides a luminescence device, comprising: anorganic compound layer comprising a metal coordination compoundrepresented by the following formula (2):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene grouphaving 2–4 carbon atoms capable of including one or at least twonon-neighboring methylene groups which can be replaced with —O—, —S— or—CO— and capable of including hydrogen atom which can be replaced with alinear or branched alkyl group having 1–10 carbon atoms; and X1 and X2independently denote hydrogen atom; halogen atom; nitro group;trialkylsilyl group having 1–8 carbon atoms; or a linear or branchedalkyl group having 1–20 carbon atoms capable of including one or atleast two non-neighboring methylene groups which can be replaced with—O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable ofincluding hydrogen atom which can be replaced with fluorine atom.

The present invention also provides a metal coordination compound,adapted for use in a luminescence device, represented by the followingformula (2):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene grouphaving 2–4 carbon atoms capable of including one or at least twonon-neighboring methylene groups which can be replaced with —O—, —S— or—CO— and capable of including hydrogen atom which can be replaced with alinear or branched alkyl group having 1–10 carbon atoms; and X1 and X2independently denote hydrogen atom; halogen atom; nitro group;trialkylsilyl group having 1–8 carbon atoms; or a linear or branchedalkyl group having 1–20 carbon atoms capable of including one or atleast two non-neighboring methylene groups which can be replaced with—O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or

and capable of including hydrogen atom which can be replaced withfluorine atom.

The present invention further provides a display apparatus including theabove-mentioned luminescence device and drive means for driving theluminescence device.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are respectively a schematic sectional view of alayer structure of a luminescence device.

FIG. 2 is a graph showing a relationship between a Hammett'ssubstitution constant σ and a peak (maximum) emission wavelength λ_(PE).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the case where a luminescence layer for an organic EL device isformed of a carrier transporting host material and a phosphorescentguest material, a process of emission of light (phosphorescence) maygenerally involve the following steps:

-   -   (1) transport of electron and hole within a luminescence layer,    -   (2) formation of exciton of the host material,    -   (3) transmission of excited energy between host material        molecules,    -   (4) transmission of excited energy from the host material        molecule to the guest material molecule,    -   (5) formation of triplet exciton of the guest material, and    -   (6) emission of light (phosphorescence) caused during transition        from the triplet excited state to the ground state of the guest        material.

In the above steps, desired energy transmission and luminescence maygenerally be caused based on various quenching and competition.

In order to improve a luminescence efficiency of the EL device, aluminescence center material per se is required to provide a higheryield of luminescence quantum. In addition thereto, an efficient energytransfer between host material molecules and/or between host materialmolecule and guest material molecule is also an important factor.

Further, the above-described luminescent deterioration in energizedstate may presumably relate to the luminescent center material per se oran environmental change thereof by its ambient molecular structure.

For this reason, our research group has extensively investigated aneffect of use of various metal coordination compounds as the luminescentcenter material and as a result, has found that the metal coordinationcompound represented by the above-mentioned formula (1) or (2) allows ahigh-efficiency luminescence with a high brightness (luminance) for along period (i.e., a decreased luminescent deterioration in energizedstate).

The metal coordination compound of formula (1) may preferably havesubstituents X1 to X8 in which at least two of X1 to X8 are substituentsother than hydrogen atom. Further, in the formula (1), at least one ofX5 to X8 may preferably be a substituent other than hydrogen atom and/orat least two of X1 to X4 may preferably be substituents other thanhydrogen atom.

The metal coordination compound represented by the formulas (1) causesphosphorescence (luminescence) and is assumed to have a lowest excitedstate comprising a triplet excited state liable to cause metal-to-ligandcharge transfer (MLCT* state). The phosphorescent emission of light(phosphorescence) is produced during the transition from the MLCT* stateto the ground state.

The metal coordination compound of formula (1) according to the presentinvention has been found to provide a higher phosphorescence yield of0.1–0.9 and a shorter phosphorescence life of 1–60 μsec.

A phosphorescence yield (P(m)) is obtained based on the followingequation:P(m)/P(s)=(S(m)/S(s))×(A(s)/A(m)),wherein P(m) represents a phosphorescence yield of an (unknown)objective luminescent material, P(s) represents a known (standard)phosphorescence yield of standard luminescent material (Ir(ppy)₃), S(m)represents an integrated intensity of (photo-)excited emission spectrumof the objective material, S(s) represents a known integrated intensityof the standard material, A(m) represents an absorption spectrum of anexcited light wavelength of the objective material, and A(s) representsa known absorption spectrum of the standard material.

The shorter phosphorescence life is necessary to provide a resultant ELdevice with a higher luminescence efficiency. This is because the longerphosphorescence life increases molecules placed in their triplet excitedstate which is a waiting state for phosphorescence, thus lowering theresultant luminescence efficiency particularly at a higher currentdensity.

Accordingly, the metal coordination compound of formula (1) according tothe present invention is a suitable luminescent material for an ELdevice with a higher phosphorescence yield and a shorter phosphorescencelife.

Further, we have found that it is possible to control an emissionwavelength of the metal coordination compound of formula (1) byappropriately modifying the substituents X1 to X8 thereof. In thisregard, as a result of our investigation on various phosphorescencemetal coordination compounds for a blue luminescence material requiredto have a peak (maximum) emission wavelength of at most 490 nm, we havefound that it is very effective to introduce at least one substituenthaving a Hammett's substituent constant of at least 0.2 into the metalcoordination compound of formula (1) in order to provide a shorter peakemission wavelength.

More specifically we investigated a relationship between Hammett'ssubstituent constants σ of substituents X2, X3 and X4 with respect tocarbon atom connected to iridium of an iridium complex (metalcoordination compound) shown below and peak emission wavelengths λ_(PE)in toluene at 25° C.

With respect to the Hammett's substituent constant σ, a Hammett'ssubstituent constant σm for meta-position was used for the substituentsX2 and X4 and a Hammett's substituent constant σp for para-position wasused for the substituent X3. When two or more substituents other thanhydrogen atom were present at X2 to X4, a sum of σm and σp was used as aHammett's substituent constant σ.

In the present invention, specific values of σm and σp described onpages 96–103 (Table 1) of “Correlation between Structure and Activationof Drugs”, Chemical Region Extra Edition 122, issued by Nanko-do (Japan)were used as those for X2 to X4. A part of σm and σp described thereinis shown in Table 1 below.

TABLE 1 Substituent σp σm F 0.06 0.34 Cl 0.23 0.37 CF₃ 0.54 0.43

For example, a metal coordination compound (Example Compound No. (121)appearing hereinafter, X2=F, X3=CF₃, X4=H) has a Hammett's substituentconstant σ=0.34+0.54=0.88. In a similar manner, Hammett's substituentconstants σ of several metal coordination compounds (Ex. Comp. Nos. (1),(32), (122) and (111) described later and the metal coordinationcompound A described in the above-mentioned Document 2) are calculatedand shown in Table 2 below together with corresponding peak emissionwavelength λ_(PE) in toluene at 25° C. The results of Table 2 are alsoshown in FIG. 2.

TABLE 2 Compound σ λ_(PE) (nm) Ex. Comp. No. (1) 0.06 522 Metalcoordination 0.40 505 compound A Ex. Comp. No. (32) 0.54 487 Ex. Comp.No. (122) 0.68 471 Ex. Comp. No. (121) 0.88 466 Ex. Comp. No. (111) 0.91479

As apparent from Table 2 and FIG. 2, introduction of substituent(s)having a larger Hammett's substituent constant is very effective toshorten the peak emission wavelength. Specifically, the metalcoordination compound having the sum of peak emission wavelengths of atleast 0.41, particularly at least 0.50 is suitable as the blueluminescent material. A similar effect can be expected also for metalcoordination compounds other than the metal coordination compound offormula (1) of the present invention.

As described above, the metal coordination compound of formula (1) is asuitable luminescent material for the EL device.

Further, as shown in Examples appearing hereinafter, it has beensubstantiated that the metal coordination compound of formula (1) of thepresent invention has an excellent stability in a continuousenergization test.

This may be attributable to introduction of particular substituents (X1to X8) allowing control of intermolecular interaction with a hostluminescent material (e.g., CBP described above) and suppression offormation of associated exciton leading to thermal quenching, thusminimizing quenching to improve device characteristics.

In this regard, the methyl group of methyl-substitutediridium-phenylpyrimidine complex described in the above-mentionedDocument 1 has a smaller bulkiness than ethyl group and methoxy groupand a smaller electronic effect than halogen atom, trifluoromethyl groupand methoxy group. As a result, the effect of controlling intermolecularinteraction in the present invention cannot be expected.

Further, compared with 4-, 5-fluorine (substituted)iridium-phenylpyrimidine complex (metal coordination compound A)described in the above-mentioned Document 2, it has been substantiatedthat a luminescence device using the metal coordination compound offormula (1) according to the present invention has a higher durability,i.e., a higher luminance stability for a long period, shown in Examplesdescribed later.

Further, in the case of phosphorescent (luminescent) material,luminescent characteristics are largely affected by its molecularenvironment. On the other hand, principal characteristics of thefluorescent material are studied based on photoluminescence.

For this reason, results of photoluminescence of the phosphorescentmaterial do not reflect luminescent characteristics of the resultant ELdevice in many cases since the luminescent characteristics in the caseof the phosphorescent material depend on a magnitude of polarity ofambient host material molecules, ambient temperature, presence state ofthe material (e.g., solid state or liquid state, etc. Accordingly,different from the fluorescent material, it is generally difficult toexpect the resultant EL characteristics for the phosphorescent materialby simply removing a part of characteristics from photoluminescenceresults.

Next, the metal coordination compound of formula (2) according to thepresent invention will be described.

The metal coordination compound of formula (2) may preferably havehydrogen atom(s) as at least one of X1 and X2 in the formula (2).

Similarly as the metal coordination compound of formula (1), the metalcoordination compound of formula (2) also causes phosphorescence(luminescence) and is assumed to have a lowest excited state comprisinga triplet excited state liable to cause metal-to-ligand charge transfer(MLCT* state). The phosphorescent emission of light (phosphorescence) isproduced during the transition from the MLCT* state to the ground state.

The metal coordination compound according to the present invention hasbeen found to provide a higher phosphorescence yield of 0.15–0.9 and ashorter phosphorescence life of 1–40 μsec, as a result of a luminescencetest based on photoluminescence by photo-excitation.

The shorter phosphorescence life is necessary to provide a resultant ELdevice with a higher luminescence efficiency. This is because the longerphosphorescence life increases molecules placed in their triplet excitedstate which is a waiting state for phosphorescence, thus lowering theresultant luminescence efficiency particularly at a higher currentdensity.

Accordingly, the metal coordination compound of formula (2) according tothe present invention is a suitable luminescent material for an ELdevice with a higher phosphorescence yield and a shorter phosphorescencelife.

Further, by appropriately modifying the alkylene group Y and/or thesubstituents X1 and X2, emission wavelength control can be expected forthe resultant metal coordination compound of formula (2).

As described above, the metal coordination compound of formula (2) is asuitable luminescent material for the EL device.

Further, as shown in Examples appearing hereinafter, it has beensubstantiated that the metal coordination compound of formula (2) of thepresent invention has an excellent stability in a continuousenergization test.

This may be attributable to introduction of particular alkylene groupand/or substituents (Y, X1, X2) allowing control of intermolecularinteraction with a host luminescent material (e.g., CBP described above)and suppression of formation of associated exciton leading to thermalquenching, thus minimizing quenching to improve device characteristics.

The luminescence device (EL) device according to the present inventionemploys the above-mentioned metal coordination compound in an organiclayer, particularly a luminescence layer.

Specifically, the luminescence device may preferably include the organiclayer comprising the metal coordination compound of formula (1) orformula (2) between a pair of oppositely disposed electrodes comprisinga transparent electrode (anode) and a metal electrode (cathode) whichare supplied with a voltage to cause luminescence, thus constituting anelectric-field luminescence device.

The luminescence device of the present invention has a layered structureshown in FIGS. 1A to 1C as specifically described above.

By the use of the metal coordination compound of formula (1) or formula(2) of the present invention, the resultant luminescence device has ahigh luminescence efficiency as described above.

The luminescence device according to the present invention may beapplicable to devices required to allow energy saving and highluminance, such as those for display apparatus and illuminationapparatus, a light source for printers, and backlight (unit) for aliquid crystal display apparatus. Specifically, in the case of using theluminescence device of the present invention in the display apparatus,it is possible to provide a flat panel display apparatus capable ofexhibiting an excellent energy saving performance, a high visibility anda good lightweight property. With respect to the light source, itbecomes possible to replace a laser light source of laser beam printercurrently used widely with the luminescence device according to thepresent invention. Further, when the luminescence device of the presentinvention is arranged in independently addressable arrays as an exposuremeans for effecting desired exposure of light to a photosensitive drumfor forming an image, it becomes possible to considerably reducing thevolume (size) of image forming apparatus. With respect to theillumination apparatus and backlight (unit), the resultant apparatus(unit) using the luminescence device of the present invention isexpected to have an energy saving effect.

The metal coordination compound of formula (1) may generally besynthesized through the following reaction scheme.

(Rhodium Complex)

Rh complex may be synthesized in the same manner as in Ir complex shownabove.

Specific and non-exhaustive examples of the metal coordination compoundof formula (1) may include those (Example Compound Nos. (1-1) to(1-180)) shown in Tables 3–8 wherein Ex. Comp. Nos. (1-1) to (1-180) aresimply indicated as (1) to (180), respectively.

TABLE 3 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈  (1) Ir 3 H H F H H H H H  (2)Ir 3 H F H H H H H H  (3) Ir 3 H H Cl H H H H H  (4) Ir 3 H H F H H OCH₃H H  (5) Ir 3 H H F H H H Br H  (6) Ir 3 H C₂H₅ H H H H H H  (7) Ir 3 HH NO₂ H H H H H  (8) Ir 3 H H NO₂ H H H CF₃ H  (9) Ir 3 H H NO₂ H H NO₂H H (10) Ir 3 H H NO₂ H H OC₁₁H₂₃ H H (11) Ir 3 H H C₃H₇ H H H H H (12)Ir 3 H C₂H₅ OCH₃ H H H H H (13) Ir 3 H H C₃H₇ H H OC₄H₉ H H (14) Ir 3 HC₂₀H₄₁ H H H H H H (15) Ir 3 H H OCH₃ H H H H H (16) Ir 3 H OCH₃ OCH₃ HH H H H (17) Ir 3 H H OCH(CH₃)₂ H H H H H (18) Ir 3 H H OC₅H₁₁ H H H H H(19) Ir 3 H H OC₁₆H₃₃ H H H H H (20) Ir 3 H H OCH₃ H H OCH₃ H H (21) Ir3 H H OCH(CH₃)₂ H H OCH₃ H H (22) Ir 3 H H OC₁₀H₂₁ H H NO₂ H H (23) Ir 3H H OCH(CH₃)₂ H H H CF₃ H (24) Ir 3 H H SCH₃ H H H H H (25) Ir 3 HOCH₂CH═CH₂ H H H H H H (26) Ir 3 H H OCH₂C≡CCH₃ H H H H H (27) Ir 3 H HCOCH₃ H H H H H (28) Ir 3 H H COCH₃ H H NO₂ H H (29) Ir 3 H H COCH₃ H HH CF₃ H (30) Ir 3 H H COCH₃ H H OCH₃ H H

TABLE 4 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (31) Ir 3 H H COC₉H₁₉ H H H H H(32) Ir 3 H H CF₃ H H H H H (33) Ir 3 H H CF₃ H H H CF₃ H (34) Ir 3 H HCF₃ H H NO₂ H H (35) Ir 3 H H CF₃ H H OCH(CH₃)₂ H H (36) Ir 3 H C₃F₇ H HH H H H (37) Ir 3 H H OCF₃ H H H H H (38) Ir 3 H OCF₃ H H H H H H (39)Ir 3 H H OCF₃ H H NO₂ H H (40) Ir 3 H H OCF₃ H H H CF₃ H (41) Ir 3 H HOCF₃ H H OCH₃ H H (42) Ir 3 H H OCH₂C₃F₇ H H H H H (43) Ir 3 HO(CH₂)₃C₂F₅ H H H H H H (44) Ir 3 H H O(CH₂)₃OCH₂C₂F₅ H H H H H (45) Ir3 H H COOC₂H₅ H H H H H (46) Ir 3 H OCOCH₃ H H H H H H (47) Ir 3 H HO(CH₂)₂C₃F₇ H H H C₅F₁₁ H (48) Ir 3 H H H H H OCH₃ H H (49) Ir 3 H H H HH H CF₃ H (50) Ir 3 H H H H H H NO₂ H (51) Ir 3 H H Si(CH₃)₃ H H H H H(52) Ir 3 H H Si(CH₃)₂C₄H₉ H H H H H (53) Ir 3 H Si(CH₃)₂C₈H₁₇ H H H H HH (54) Ir 3 H H Si(C₂H₅)₃ H H H H H (55) Ir 3 H H H H H Si(CH₃)₂C₆H₁₃ HH (56) Ir 3 H C₂H₅ OCH₃ H H OCH₃ H H (57) Ir 3 H F H F H OCH₃ H H (58)Ir 3 H F H F H OCH₃ CF₃ H (59) Ir 3 H H Si(CH₃)₃ H H H Br H (60) Ir 3 HSi(CH₃)₂C₇H₁₅ OCH₃ H H H H H

TABLE 5 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (61) Rh 3 H H F H H H H H (62)Rh 3 F F H H H H H H (63) Rh 3 H H F H H OCH₃ H H (64) Rh 3 H H NO₂ H HH H H (65) Rh 3 H H NO₂ H H OC₈H₁₇ H H (66) Rh 3 H H C₂H₅ H H H H H (67)Rh 3 H C₂H₅ OCH₃ H H H H H (68) Rh 3 H C₁₂H₂₅ H H H H H H (69) Rh 3 HC₃H₇ H H H OCH₃ H H (70) Rh 3 H H OCH(CH₃)₂ H H H H H (71) Rh 3 H HOC₁₅H₃₁ H H H H H (72) Rh 3 H H OC₆H₁₃ H H NO₂ H H (73) Rh 3 H H OCH₃ HH OCH₃ H H (74) Rh 3 H H OCH(CH₃)₂ H H H CF₃ H (75) Rh 3 H H OCH₂CH═CH₂H H H H H (76) Rh 3 H OC≡CC₄H₉ H H H H H H (77) Rh 3 H H SC₂H₅ H H H H H(78) Rh 3 H H SCH₃ H H OCH₃ H H (79) Rh 3 H SCH₃ SCH₃ H H H H H (80) Rh3 H H COCH₃ H H H H H (81) Rh 3 H H COCH₃ H H OCH₃ H H (82) Rh 3 H H CF₃H H H H H (83) Rh 3 H H CF₃ H H OCH(CH₃)₂ H H (84) Rh 3 H H OCF₃ H H HCF₃ H (85) Rh 3 H H OCH₂C₄F₉ H H H H H (86) Rh 3 H H O(CH₂)₆C₂F₅ H H H HH (87) Rh 3 H H H H H OCH₃ H H (88) Rh 3 H H Si(CH₃)₃ H H H H H (89) Rh3 H Si(CH₃)₂C₆H₁₃ H H H H H H (90) Rh 3 H Si(CH₃)₂C₇H₁₅ OCH₃ H H H H H

TABLE 6 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈  (91) Pd 2 H H F H H H H H  (92)Pd 2 H F H F H H H H  (93) Pd 2 H H F H H OC₇H₁₅ H H  (94) Pd 2 H H NO₂H H H H H  (95) Pd 2 H H NO₂ H H OC₅H₁₁ H H  (96) Pd 2 H C₂H₅ OCH₃ H H HH H  (97) Pd 2 H H C₅H₁₁ H H OCH₃ H H  (98) Pd 2 H C₁₅H₃₁ H H H H H H (99) Pd 2 H H OCH(CH₃)₂ H H H H H (100) Pd 2 H H OC₃H₇ H H H H H (101)Pd 2 H H COC₈H₁₇ H H H H H (102) Pd .2 H H CF₃ H H H H H (103) Pd 2 H HCF₃ H H OCH(CH₃)₂ H H (104) Pd 2 H H OCF₃ H H H CF₃ H (105) Pd 2 H HSi(CH₃)₃ H H H H H (106) Pd 2 H H F H H OC₅H₁₁ H H (107) Pd 2 H H NO₂ HH OC₃H₇ H H (108) Pd 2 H H C₂H₅ H H OCH₃ H H (109) Pd 2 H C₁₀H₂₁ H H H HH H (110) Pd 2 H H COCH₃ H H H H H (111) Ir 3 H Cl CF₃ H H H H H (112)Ir 3 H Cl CF₃ H H H CF3 H (113) Ir 3 H Cl CF₃ H H OCH3 H H (114) Rh 3 HCl CF₃ H H H H H (115) Rh 3 H Cl CF₃ H H H CF3 H (116) Rh 3 H Cl CF₃ H HCF3 H H (117) Rh 3 H Cl CF₃ H H OCH3 H H (118) Rh 3 H Cl CF₃ H H C₂H₅ HH (119) Pd 2 H Cl CF₃ H H H H H (120) Pd 2 H Cl CF₃ H H H CF3 CF3

TABLE 7 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (121) Ir 3 H F CF₃ H H H H H(122) Ir 3 H F H F H H H H (123) Ir 3 H CF₃ H CF₃ H H H H (124) Ir 3 HCF₃ H F H H H H (125) Ir 3 H CF₃ CF₃ H H H Br H (126) Ir 3 F C₂H₅ H H HH H H (127) Ir 3 F H NO₂ H H H H H (128) Ir 3 F H NO₂ F H H CF₃ H (129)Ir 3 F H NO₂ H H NO₂ H H (130) Ir 3 F H NO₂ H H OC₁₁H₂₃ H H (131) Ir 3 FH C₃H₇ H H H H H (132) Ir 3 F C₂H₅ OCH₃ H H H H H (133) Ir 4 F H C₃H₇ HH OC₄H₉ H H (134) Ir 3 H C₂₀H₄₁ H F H H H H (135) Ir 3 H H OCH₃ F H H HH (136) Ir 3 H OCH₃ OCH₃ F H H H H (137) Ir 3 H H OCH(CH₃)₂ F H H H H(138) Ir 3 H H OC₅H₁₁ F H H H H (139) Ir 3 H H OC₁₆H₃₃ F H H H H (140)Ir 3 H H OCH₃ F H OCH₃ H H (141) Ir 3 H H OCH(CH₃)₂ H F OCH₃ H H (142)Ir 3 H H OC₁₀H₂₁ H F NO₂ H H (143) Ir 3 H H OCH(CH₃)₂ H F H CF₃ H (144)Ir 3 H H SCH₃ H C₂H₅ H H H (145) Ir 3 H OCH₂CH═CH₂ H H C₂H₅ H H H (146)Ir 3 H H OCH₂C≡CCH₃ H H H H F (147) Ir 3 H H COCH₃ H H H H F (148) Ir 3H H COCH₃ H H NO₂ H F (149) Ir 3 H H COCH₃ H H H CF₃ F (150) Ir 3 CF₃ HCOCH₃ H H OCH₃ H H

TABLE 8 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (151) Ir 3 F H COC₉H₁₉ H H H H H(152) Ir 3 H CF₃ H F H H H H (153) Ir 3 F H CF₃ H H H CF₃ H (154) Ir 3 HH CF₃ F H NO₂ H H (155) Ir 3 H H CF₃ F H OCH(CH₃)₂ H H (156) Ir 3 H C₃F₇H CF₃ H H H H (157) Ir 3 H H OCF₃ H CF₃ H H H (158) Ir 3 H OCF₃ H H C₂H₅H H H (159) Ir 3 H CF₃ H CF₃ H H H H (160) Ir 3 H H OCF₃ H F H CF₃ H(161) Ir 3 H H OCF₃ H H OCH₃ H F (162) Ir 3 H H OCH₂C₃F₇ H H H H F (163)Ir 3 H O(CH₂)₃C₂F₅ H H H H H F (164) Ir 3 H H O(CH₂)₃OCH₂C₂F₅ Cl H H H H(165) Ir 3 H H COOC₂H₅ F H H H H (166) Rh 3 H OCOCH₃ H H F H H H (167)Rh 3 H H O(CH₂)₂C₃F₇ H C₂H₅ H C₅F₁₁ H (168) Rh 3 H H H H H OCH₃ H F(169) Rh 3 H H H H H H CF₃ F (170) Rh 3 H H H H H H NO₂ F (171) Rh 3 H HSi(CH₃)₃ H H H H F (172) Rh 3 H H Si(CH₃)₂C₄H₉ H H H H F (173) Rh 3 HSi(CH₃)₂C₈H₁₇ H F H H H H (174) Rh 3 H H Si(C₂H₅)₃ F H H H H (175) Rh 3H H H F H Si(CH₃)₂C₆H₁₃ H H (176) Pd 2 H C₂H₅ OCH₃ F H OCH₃ H H (177) Pd2 F H F F H OCH₃ H H (178) Pd 2 F H F F H OCH₃ CF₃ H (179) Pd 2 F HSi(CH₃)₃ H H H Br H (180) Pd 2 F Si(CH₃)₂C₇H₁₅ OCH₃ H H H H H

The metal coordination compound of formula (2) may generally besynthesized through the following reaction scheme.

(Rhodium Complex)

Rh complex may be synthesized in the same manner as in Ir complex shownabove.

Specific and non-exhaustive examples of the metal coordination compoundof formula (2) may include those (Example Compound Nos. (2-1) to (2-200)shown in Tables 9–15 wherein Ex. Comp. Nos. (2-1) to (2-200) are simplyindicated as (1) to (200), respectively.

In Tables 9–15, symbols A to C′ for alkylene group Y represents alkylenegroups shown below.

TABLE 9 No. M n Y R₁ R₂ X₁ X₂ (1) Ir 3 A — — H H (2) Ir 3 A — — OCH₃ H(3) Ir 3 B H — H H (4) Ir 3 B H — OCH₃ H (5) Ir 3 B H — H CF₃ (6) Ir 3 BH — H Cl (7) Ir 3 B CH₃ — H H (8) Ir 3 B CH₃ — F H (9) Ir 3 B CH₃ — NO₂H (10) Ir 3 B C₂H₅ — H H (11) Ir 3 B C₃H₇ — H CF₃ (12) Ir 3 BC₂H₅(CH₃)CHCH₂ — H H (13) Ir 4 B C₆H₁₃ — OCH(CH₃)₂ H (14) Ir 3 B C₁₀H₂₁— S(CH₃)₃ H (15) Ir 3 C H H H H (16) Ir 3 C H H OCH₃ H (17) Ir 3 C H H HCF₃ (18) Ir 3 C H H F H (19) Ir 3 C H H NO₂ H (20) Ir 3 C H H OC₅H₁₁ H(21) Ir 3 C H H O(CH₂)₂C₃F₇ H (22) Ir 3 C H H H Si(C₂H₅)₃ (23) Ir 3 C HH H Br (24) Ir 3 C H H CH₃ H (25) Ir 3 C CH₃ H CH₃ H (26) Ir 3 C H CH₃ HH (27) Ir 3 C CH₃ CH₃ H H (28) Ir 3 C C₃H₇ H Si(CH₃)₃ H (29) Ir 3 C HC₅H₁₁ H H (30) Ir 3 C C₈H₁₇ H Cl H

TABLE 10 No. M n Y R₁ R₂ X₁ X₂ (31) Ir 3 C C₂H₅ C₂H₅ H C₇F₁₅ (32) Ir 3 CH C₆H₁₃ NO₂ H (33) Ir 3 C C₁₀H₂₁ H CF₃ H (34) Ir 3 C H C₉H₁₉ H OC₄H₉(35) Ir 3 D — — H H (36) Ir 3 D — — OCH₃ H (37) Ir 3 E H — H H (38) Ir 3E H — H NO₂ (39) Ir 3 E CH₃ — H H (40) Ir 3 E CH₃ — OCH₃ H (41) Ir 3 ECH₃ — H CF₃ (42) Ir 3 E CH₃ — NO₂ H (43) Ir 3 E CH₃ — OC₃H₇ H (44) Ir 3E C₂H₅ — H H (45) Ir 3 E C₂H₅ — H CF₃ (46) Ir 3 E C₃H₇ — H H (47) Ir 3 EC₃H₇ — OC₅H₁₁ H (48) Ir 3 E (CH₃)₂CHCH₂CH₂ — H H (49) Ir 3 E C₅H₁₁ — HC₄F₉ (50) Ir 3 E C₆H₁₃ — H H (51) Ir 3 E C₉H₁₃ — H Br (52) Ir 3 E C₆H₁₃— NO₂ H (53) Ir 3 E C₈H₁₇ — H H (54) Ir 3 E C₉H₁₉ — OCH₂C≡CCH₃ H (55) Ir3 E C₁₀H₂₁ — H H (56) Ir 3 E C₁₀H₂₁ — OCH₂CH═CH₂ H (57) Ir 3 F H — OCH₃H (58) Ir 3 F CH₃ — H H (59) Ir 3 F CH₃ — OCH₃ H (60) Ir 3 F C₂H₅ — HCF₃

TABLE 11 No. M n Y R₁ R₂ X₁ X₂ (61) Ir 3 F C₆H₁₃ — OCH(CH₃)₂ H (62) Ir 3F C₈H₁₇ — Si(CH₃)₂C₈H₁₇ H (63) Ir 3 G H — OCH₃ H (64) Ir 3 G H — H CF₃(65) Ir 3 G H — O(CH₂)₃OCH₂C₂F₅ H (66) Ir 3 G CH₃ — H H (67) Ir 3 H H HH H (68) Ir 3 H CH₃ H Si(C₃)₃ H (69) Ir 3 H H CH₃ H Cl (70) Ir 3 I H H HH (71) Ir 3 I H H OCH₃ H (72) Ir 3 I H H H CF₃ (73) Ir 3 I H H H CH₃(74) Ir 3 I C₂H₅ H COOC₂H₅ H (75) Ir 3 I H C₅H₁₁ OCH₂CH═CH₂ H (76) Ir 3J H — H H (77) Ir 3 J H — NO₂ H (78) Ir 3 J CH₃ — OCH₃ H (79) Ir 3 K H —H H (80) Ir 3 K H — H Si(CH₃)₃ (81) Ir 3 K C₃H₇ — H CF₃ (82) Ir 3 L H HH H (83) Ir 3 L CH₃ H SC₂H₅ H (84) Ir 3 L H CH₃ OC₆H₁₃ H (85) Ir 3 M H HH H (86) Ir 3 M C₂H₅ H COOC₃H₇ H (87) Ir 3 M H C₂H₅ H O(CH₂)₃C₂F₅ (88)Ir 3 N — H H H (89) Ir 3 N — C₂H₅ H NO₂ (90) Ir 3 N — C₆H₁₃ Cl H

TABLE 12 No. M n Y R₁ R₂ X₁ X₂  (91) Ir 3 O H — H H  (92) Ir 3 O H — HSi(C₂H₅)₃  (93) Ir 3 O C₈H₁₇ — OCH(CH₃)₂ H  (94) Ir 3 P H — H H  (95) Ir3 P C₃H₇ — H COOCH₃  (96) Ir 3 P C₆H₁₃ — H H  (97) Ir 3 Q H — H H  (98)Ir 3 Q C₄H₉ — O(CH₂)₃CH═CH₂ H  (99) Ir 3 R — — H H (100) Ir 3 R — — HCF₃ (101) Ir 3 S — — H H (102) Ir 3 S — — OC₂H₅ H (103) Ir 3 T H — H Br(104) Ir 3 T C₂H₅ — H H (105) Ir 3 U — — H H (106) Ir 3 U — — H C₇F₁₅(107) Ir 3 V H — H H (108) Ir 3 W — — OCH₂C≡CCH₃ H (109) Ir 3 X CH₃ — HH (110) Ir 3 Z — H O(CH₂)₂CH(CH₃)₂ H (111) Ir 3 Z — C₃H₇ H H (112) Ir 3A′ H H H H (113) Ir 3 B′ H — H NO₂ (114) Ir 3 B′ CH₃ — H H (115) Ir 3 C′H C₉H₁₉ OCH₃ H (116) Pt 2 A — — H H (117) Pt 2 B H — H H (118) Pt 2 B H— H C₄F₉ (119) Pt 2 B CH₃ — OCH₃ H (120) Pt 2 B C₃H₇ — H CF₃

TABLE 13 No. M n Y R₁ R₂ X₁ X₂ (121) Pt 2 B C₈H₁₇ — H H (122) Pt 2 C H HH H (123) Pt 2 C H H H CF₃ (124) Pt 2 C CH₃ CH₃ H H (125) Pt 2 C C₂H₅ HH H (126) Pt 2 C C₁₀H₂₁ H OCH₃ H (127) Pt 2 D — — H H (128) Pt 2 E H — HH (129) Pt 2 E CH₃ — H H (130) Pt 2 E CH₃ — H H (131) Pt 2 E CH₃ — H NO₂(132) Pt 2 E C₆H₁₃ — OC₂H₅ H (133) Pt 2 F CH₃ — H H (134) Pt 2 F C₂H₅ —H CF₃ (135) Pt 2 G H — H H (136) Pt 2 G H — H Si(CH₃)₃ (137) Pt 2 G C₄H₉— H CH₃ (138) Pt 2 H H C₆H₁₃ H H (139) Pt 2 I H H H H (140) Pt 2 I C₂H₅H H Si(C₂H₅)₃ (141) Pt 2 J — H H H (142) Pt 2 K C₅H₁₁ — H H (143) Pt 2 LC₈H₁₇ H SC₂H₅ H (144) Pt 2 N — H H H (145) Pt 2 O H — H H (146) Pt 2 P H— H H (147) Pt 2 Q H — H CH₃ (148) Pt 2 R — — H H (149) Pt 2 U — — H H(150) Pt 2 V H — NO₂ H

TABLE 14 No. M n Y R₁ R₂ X₁ X₂ (151) Pt 2 W — — H H (152) Pt 2 X CH₃ — HH (153) Pt 2 Z — H H H (154) Pt 2 A′ H H H H (155) Pt 2 B′ H — OCH₃ H(156) Pt 2 C′ H H H CF₃ (157) Rh 3 B H — H Br (158) Rh 3 B H — OC₆H₁₃ H(159) Rh 3 B CH₃ — H H (160) Rh 3 C H H H H (161) Rh 3 C H H OCH₃ H(162) Rh 3 C H H NO₂ H (163) Rh 3 C H CH₃ H H (164) Rh 3 C C₆H₁₃ H HSi(CH₃)₃ (165) Rh 3 D — — H H (166) Rh 3 E H — COOC₂H₅ H (167) Rh 3 ECH₃ — H H (168) Rh 3 E CH₃ — H O(CH₂)₆C₂F₅ (169) Rh 3 E C₃H₇ — H H (170)Rh 3 E C₁₀H₂₁ — H H (171) Rh 3 F C₈H₁₇ — H H (172) Rh 3 G H — OCH₂CH═CH₂H (173) Rh 3 G CH₃ — H CF₃ (174) Rh 3 H H H H H (175) Rh 3 I H H H H(176) Rh 3 K C₂H₅ — Cl H (177) Rh 3 M H H H H (178) Rh 3 N — H H H (179)Rh 3 P CH₃ — H NO₂ (180) Rh 3 S — — H H

TABLE 15 No. M n Y R₁ R₂ X₁ X₂ (181) Rh 3 V H — H H (182) Rh 3 X H —SC₅H₁₁ H (183) Rh 3 C′ H OC₇H₁₅ H (184) Pd 2 B C₆H₁₃ — H H (185) Pd 2 CH H OCH₃ H (186) Pd 2 C H H H H (187) Pd 2 D — — H H (188) Pd 2 E H — HCF₃ (189) Pd 2 E CH₃ — H H (190) Pd 2 F C₃H₇ — H H (191) Pd 2 G H — H H(192) Pd 2 G H — Si(CH₃)₃ H (193) Pd 2 I CH₃ H NO₂ H (194) Pd 2 J — H HH (195) Pd 2 L H H H H (196) Pd 2 M H H C₄F₉ H (197) Pd 2 O H — H C₄H₉(198) Pd 2 T H — H H (199) Pd 2 W — — OCH₃ OCH₃ (200) Pd 2 A′ CH₃ H H Cl

Hereinbelow, the present invention will be described more specificallybased on Examples with reference to the drawing.

EXAMPLES I-1–I-10

In these examples, metal coordination compounds of formula (1) (Ex.Comp. Nos. (I-4), (I-7), (I-17), (I-18), (I-21), (I-23), (I-32), (I-56),(I-67) and (I-74) were used in respective luminescence layers forExamples I-1–I-10, respectively.

Each of luminescence devices having a structure shown in FIG. 1B wereprepared in the following manner.

On a glass substrate (transparent substrate 15), a 100 nm-thick film(transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP: metalcoordination compound of formula (1) (95:5 by weight)

Organic layer 3 (electron transport layer 16) (30 nm): Alq3

Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

Metal electrode layer 2 (metal electrode 11) (100 nm): Al

Each of the thus-prepared luminescence devices was taken out of thevacuum chamber and was subjected to a continuous energization test in anatmosphere of dry nitrogen gas stream so as to remove devicedeterioration factors, such as oxygen and moisture (water content).

The continuous energization test was performed by continuously applyinga voltage at a constant current density of 70 mA/cm² to the luminescencedevice having the ITO (transparent) electrode (as an anode) and the Al(metal) electrode (as a cathode), followed by measurement of luminance(brightness) with time so as to determine a time (luminance half-life)required for decreasing an initial luminance (70–120 cd/m²) to ½thereof.

The results are shown in Table 16 appearing hereinafter.

COMPARATIVE EXAMPLE I-1

A comparative luminescence device was prepared and evaluated in the samemanner as in Example I-1–I-10 except that the metal coordinationcompound of formula (1) was changed to Ir-phenylpyridine complex(Ir(ppy)₃) shown below.

The results are shown in Table 16 below.

TABLE 16 Luminance Ex. Comp. No. half-life (Hr) Ex. No. I-1 (I-4) 750I-2 (I-7) 500 I-3 (I-17) 900 I-4 (I-18) 850 I-5 (I-21) 850 I-6 (I-23)500 I-7 (I-32) 600 I-8 (I-56) 700 I-9 (I-67) 400 I-10 (I-74) 450 Comp.Ex. I-1 Ir(ppy)₃ 350

As is apparent from Table 16, compared with the conventionalluminescence device using Ir(ppy)₃, the luminescence devices using themetal coordination compounds of formula (1) according to the presentinvention provide longer luminance half-lifes, thus resulting in an ELdevice having a high durability (luminance stability) based on a goodstability of the metal coordination compound of formula (1) of thepresent invention.

Examples I-11–I-13

In these examples, metal coordination compounds of formula (1) (Ex.Comp. Nos. (I-1), (I-32) and (I-49) were used in respective luminescencelayers for Examples I-11–I-13, respectively.

Each of luminescence devices having a structure shown in FIG. 1C wereprepared in the following manner.

On a glass substrate (transparent substrate 15), a 100 nm-thick film(transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP: metalcoordination compound of formula (1) (93:7 by weight)

Organic layer 3 (exciton diffusion prevention layer 17) (10 nm): BCP

Organic layer 4 (electron transport layer 16) (30 nm): Alq3

Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

Metal electrode layer 2 (metal electrode 11) (100 nm): Al

Separately, each of the metal coordination compounds of formula (1) (Ex.Comp. Nos. (I-1), (I-32) and (I-49)) for the thus-prepared luminescencedevices was subjected to measurement of photoluminescence spectrum inorder to evaluate a luminescent characteristic of the metal coordinationcompounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49)).Specifically, each of the metal coordination compounds was dissolved intoluene at a concentration of 10⁻⁴ mol/l and subjected to measurement ofphotoluminescence spectrum at 25° C. by using excited light (ca. 350 nm)and a spectrophoto-fluorometer (“Model F4500”, mfd. by Hitachi K.K.).

The results are shown in Table 17 appearing hereinafter.

The values of photoluminescence spectrum of the metal coordinationcompounds (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) were substantiallyequivalent to those in the luminescence devices under voltageapplication as shown in Table 17, whereby it was confirmed thatluminescence caused by the luminescence device was based on luminescenceof the metal coordination compound used.

EL characteristics of the luminescence devices using the metalcoordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and(I-49)) were measured by using a microammeter (“Model 4140B”, mfd. byHewlett-Packard Co.) for a current density under application of avoltage of 12 volts (current-voltage characteristic), using aspectrophotofluoro-meter (“Model SR1”, mfd. by Topcon K.K.) for a peakemission wavelength λ_(PE) (luminescence spectrum), and using aluminance meter (“Model BM7”, mfd. by Topcon K.K.) for a luminescenceefficiency (luminescence luminance). Further, an energy conversionefficiency was obtained according to the following equation:

$\text{Energy~~conversion~~efficiency~~(lm/W)} = {\frac{( {\pi \times \text{luminescence efficiency~~(cd/A)}} )}{\text{applied~~voltage~~(V)}}.}$

All the above-prepared luminescence devices showed a good rectificationcharacteristic.

The results are shown in Table 17.

COMPARATIVE EXAMPLE I-2

A comparative luminescence device was prepared and evaluated in the samemanner as in Example I-2–I-13 except that the metal coordinationcompound of formula (1) was changed to Ir-phenylpyridine complex(Ir(ppy)₃) shown below.

The results are shown in Table 17 below.

TABLE 17 λ PE in toluene λ PE Energy conversion Luminescence Currentdensity Luminance Ex. No Ex. Comp. No. (nm) (nm) efficiency (lm/W)efficiency (cd/A) (mA/cm² at 12 V) half-life (Hr) I-11 (I-1)  522 5254.0 13.6 170 300 I-12 (I-32) 487 525 0.4 2.4 130 400 I-13 (I-49) 537 5452.1 7.0 25 250 Comp. Ex. I-2 Ir(ppy)₃ 510 510 6.0 19.0 20 150

As shown in Table 17, compared with the luminescence device usingIr(ppy)₃ (Comparative Example I-2) showing λ_(PE)=510 nm, theluminescence devices using the metal coordination compound of formula(1) according to the present invention showed longer peak emissionwavelengths (λ_(PE)=525–545 nm) by 15–35 nm, thus resulting in smallerrelative luminous efficiencies.

Smaller energy conversion efficiencies (0.4–4.0 lm/W) and luminescenceefficiencies (2.4–13.6 cd/A) of the luminescence devices of the presentinvention compared with those (6.0 lm/W and 19.0 cd/A) of theluminescence device using Ir(ppy)₃ may be attributable to the smallerrelative luminous efficiencies due to the longer peak emissionwavelengths, thus not resulting in essentially inferior luminescentcharacteristics of the luminescence devices using the metal coordinationcompound of formula (1) of the present invention.

As apparent from the results of the luminance half-lifes of theluminescence devices, compared with the luminescence device usingIr(ppy)₃ showing the luminance half-life of 150 hours, the luminescencedevices using the metal coordination compounds of formula (1) accordingto the present invention showed considerably longer luminance half-lifesof 250–400 hours.

EXAMPLE I-14 Synthesis of Ex. Comp. No. (I-1)

In a 1 liter-three necked flask, 20.0 g (126.6 mM) of 2-bromopyridine,17.7 g (126.4 mM) of 3-fluorophenylbronic acid, 130 ml of toluene, 65 mlof ethanol and 130 ml of 2M-sodium carbonate aqueous solution wereplaced and stirred in a nitrogen gas stream at room temperature. Understirring, to the mixture, 4.60 g (3.98 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by heat-refluxingfor 6 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene. The organic layer was washedwith water until the system showed neutral, followed by distilling offof the solvent under reduced pressure to obtain a residue. The residuewas purified by silica gel column chromatography (eluent: toluene/ethylacetate=5/1) to obtain 6.0 g of 2-(3-fluorophenyl)pyridine (pale brownliquid) (Yield: 34.6%).

In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.04 g (6.00 mM) of 2-(3-fluorophenyl)pyridineand 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added,followed by heat-refluxing for 10 hours under stirring in nitrogen gasstream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 300 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by drying for 5hours at 100° C. under reduced pressure and purification by silica gelcolumn chromatography (eluent: chloroform) to obtain 0.22 g of Iridium(III) tris[2-(3-fluorophenyl)pyridine] (yellow powder) (Yield: 31.0%).

EXAMPLE I-15 Synthesis of Ex. Comp. No. (I-32)

In a 1 liter-three necked flask, 20.8 g (131.6 mM) of 2-bromopyridine,25.0 g (131.6 mM) of 3-trifluoromethylphenylbronic acid, 130 ml oftoluene, 65 ml of ethanol and 130 ml of 2M-sodium carbonate aqueoussolution were placed and stirred in a nitrogen gas stream at roomtemperature. Under stirring, to the mixture, 4.76 g (4.12 mM) oftetrakis (triphenylphosphine) palladium (0) was added, followed byheat-refluxing for 7 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene. The organic layer was washedwith water until the system showed neutral, followed by distilling offof the solvent under reduced pressure to obtain a residue (pale brownliquid). The residue was purified by silica gel column chromatography(eluent: toluene/hexane=1/1) to obtain 6.0 g of2-(3-trifluoromethylphenyl)pyridine (pale brown liquid) (Yield: 21.1%).

In a 200 ml-four necked flask, 100 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 2.68 g (12.0 mM) of2-(3-trifluoromethylphenyl)pyridine and 1.00 g (2.04 mM) of Iridium(III) acetylacetonate were added, followed by heat-refluxing for 10hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 600 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by drying for 5hours at 100° C. under reduced pressure. The precipitate was dissolvedin chloroform and the insoluble matter was removed by filtration,followed by purification by silica gel column chromatography (eluent:chloroform) and recyrstallization from a mixture solvent(chloroform/methanol) to obtain 0.62 g of Iridium (III)tris[2-(3-trifluoromethylphenyl)-pyridine] (yellow powder) (Yield:35.3%), which showed a peak emission wavelength λ_(PE) in toluene at 25°C. of 487 nm.

EXAMPLE I-16 Synthesis of Ex. Comp. No. (I-49)

In a 1 liter-three necked flask, 25.6 g (141.0 mM) of2-chloro-5-trifluoromethylpyridine, 17.2 g (141.0 mM) of phenylbronicacid, 140 ml of toluene, 70 ml of ethanol and 140 ml of 2M-sodiumcarbonate aqueous solution were placed and stirred in a nitrogen gasstream at room temperature. Under stirring, to the mixture, 5.10 g (4.41mM) of tetrakis (triphenylphosphine) palladium (0) was added, followedby heat-refluxing for 6 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene. The organic layer was washedwith water until the system showed neutral, followed by distilling offof the solvent under reduced pressure to obtain a residue. The residuewas purified by silica gel column chromatography (eluent:toluene/hexane=5/1). The resultant creamy crystal was purified byalumina column chromatography (eluent: toluene) and recrystallized fromethanol to obtain 13.1 g of 2-phenyl-5-trifluoromethylpyridine(colorless crystal) (Yield: 41.6%).

In a 200 ml-four necked flask, 100 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 2.68 g (12.0 mM) of2-phenyl-5-trifluoromethylpyridine and 1.00 g (2.04 mM) of Iridium (III)acetylacetonate were added, followed by heat-refluxing for 8 hours understirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 600 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by drying for 4hours at 100° C. under reduced pressure and purification by silica gelcolumn chromatography (eluent: chloroform) to obtain 0.43 g of Iridium(III) tris-(2-phenyl-5-trifluoromethylpyridine) (orange powder) (Yield:24.5%).

EXAMPLE I-17 Synthesis of Ex. Comp. No. (I-122)

In a 100 ml-three necked flask, 3.16 g (19.9 mM) of 2-bromopyridine,3.16 g (20.0 mM) of 2,4-difluorophenylbronic acid, 15 ml of toluene, 7.5ml of ethanol and 15 ml of 2M-sodium carbonate aqueous solution wereplaced and stirred in a nitrogen gas stream at room temperature. Understirring, to the mixture, 0.72 g (0.62 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by heat-refluxingfor 8 hours and 40 minutes under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled, followed byextraction with cool water and ethyl acetate. The organic layer waswashed with water followed by distilling off of the solvent underreduced pressure to obtain a residue. The residue was purified by silicagel column chromatography (eluent: toluene/ethyl acetate=10/1) to obtain3.28 g of 2-(2,4-difluorophenyl)pyridine (pale yellow oily product)(Yield: 86.0%).

In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 0.96 g (5.02 mM) of2-(2,4-difluorophenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III)acetylacetonate were added, followed by heat-refluxing for 10 hoursunder stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 300 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by drying for 5hours at 100° C. under reduced pressure and purification by silica gelcolumn chromatography (eluent: chloroform) and recrystallization from amixture solvent (chloroform/methanol) to obtain 0.25 g of Iridium (III)tris[2-(4,6-difluorophenyl)-pyridine] (yellow powder) (Yield: 32.1%),which showed a peak emission wavelength λ_(PE) in toluene at 25° C. of471 nm.

EXAMPLE I-18 Synthesis of Ex. Comp. No. (I-121)

In a 500 ml-three necked flask, 11.0 g (45.3 mM) of5-bromo-2-fluorobenzotrifluoride and 90 ml of dry tetrahydrofuran (THF)were placed and stirred in a nitrogen gas stream at room temperature.Under stirring, to the mixture, 2.60 g (2.25 mM) oftetrakis(triphenylphosphine) palladium (0) was added, followed bycooling to 20–21° C. (inner temperature) on an ice bath in nitrogen gasstream. At that temperature, 90 ml of 0.5 M-THF solution of2-pyridylzinc bromide was gradually added dropwise to the mixture innitrogen gas stream, followed by stirring for 4 hours at thattemperature.

After the reaction, the reaction mixture was poured into cool water,followed by addition of ethyl acetate to remove the insoluble matter byfiltration. The organic layer was washed with water and dried withanhydrous sodium sulfate, followed by distilling-off of the solventunder reduced pressure to obtain a residue.

The residue was purified by silica gel column chromatography (eluent:hexane/ethyl acetate=20/1) to obtain 1.80 g of2-(4-fluoro-3-trifluoromethylphenyl)pyridine (pale brown oily product)(Yield: 16.6%).

In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.21 g (5.02 mM) of2-(4-fluoro-3-trifluoromethylphenyl)pyridine and 0.50 g (1.02 mM) ofIridium (III) acetylacetonate were added, followed by heat-refluxing for10 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 300 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by drying for 5hours at 100° C. under reduced pressure and purification by silica gelcolumn chromatography (eluent: chloroform) and recrystallization from amixture solvent (chloroform/methanol) to obtain 0.20 g of Iridium (III)tris[2-(4-fluoro-5-trifluoromethylphenyl)pyridine] (yellow powder)(Yield: 21.5%), which showed a peak emission wavelength λ_(PE) intoluene at 25° C. of 466 nm.

EXAMPLE I-19 Synthesis of Ex. Comp. No. (I-111)

In a 500 ml-three necked flask, 11.8 g (45.5 mM) of5-bromo-2-chlorobenzotrifluoride and 90 ml of dry tetrahydrofuran (THF)were placed and stirred in a nitrogen gas stream at room temperature.Under stirring, to the mixture, 2.60 g (2.25 mM) oftetrakis(triphenylphosphine) palladium (0) was added, followed bycooling to 13.5–14° C. (inner temperature) on an ice bath in nitrogengas stream. At that temperature, 90 ml of 0.5 M-THF solution of2-pyridylzinc bromide was gradually added dropwise to the mixture innitrogen gas stream, followed by stirring for 3 hours at ca. 20° C.

After the reaction, the reaction mixture was poured into cool water,followed by addition of ethyl acetate to remove the insoluble matter byfiltration. The organic layer was washed with water and dried withanhydrous sodium sulfate, followed by distilling-off of the solventunder reduced pressure to obtain a residue. The residue was purified bysilica gel column chromatography (eluent: hexane/ethyl acetate=10/1) toobtain 3.70 g of 2-(4-chloro-5-trifluoromethylphenyl)pyridine (palebrown oily product) (Yield: 31.9%).

In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.29 g (5.01 mM) of2-(4-chloro-3-trifluoromethylphenyl)pyridine and 0.50 g (1.02 mM) ofIridium (III) acetylacetonate were added, followed by heat-refluxing for8 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 300 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by drying for 5hours at 100° C. under reduced pressure and purification by silica gelcolumn chromatography (eluent: chloroform) and recrystallization from amixture solvent (chloroform/hexane) to obtain 0.25 g of Iridium (III)tris[2-(4-chloro-3-trifluoromethylphenyl)pyridine] (yellow powder)(Yield: 25.4%), which showed a peak emission wavelength λ_(PE) intoluene at 25° C. of 479 nm.

COMPARATIVE EXAMPLE I-3 Synthesis of Metal Coordination Compound A

A metal coordination compound A (iridium (III)tris[2-(4,5-difluoromethylphenyl)pyridine described in PolymerPreprints, 41(1), pp. 770–771 (2000)) was prepared in the same manner asin Example 17 except that 2,4-difluorophenylbronic acid was changed to3,4-difluorophenylbronic acid.

The metal coordination compound A showed a peak emission wavelengthλ_(PE) in toluene at 25° C. of 505 nm.

EXAMPLE I-20 and COMPARATIVE EXAMPLE I-4

Two luminescence devices were prepared and evaluated in the same manneras in Examples I-1 to I-10 except that the metal coordination compoundwas changed to one (Ex. Comp. No. (122)) prepared in Example I-18 (forExample I-20) and the metal coordination compound A prepared inComparative Example 3 (for Comparative Example 4), respectively.

The results are shown in Table 18 below.

TABLE 18 Luminance Ex. Comp. No. half-life (Hr) Ex. No. I-20 (I-122) 630Comp. Ex. I-4 Metal coordination 310 compound A

As apparent from Table 18, the luminescence device using the metalcoordination compound of formula (1) according to the present inventionexhibited a luminance half-life considerably longer than that of theluminescence device using the metal coordination compound A, thusresulting in an EL device excellent in durability (luminance stability).

As described hereinabove, the metal coordination compound of formula (1)according to the present invention provides a higher phosphorescenceefficiency and a shorter phosphorescence life and allows control of itsemission wavelength by appropriately modifying the substituents X1 toX8, thus being suitable as a luminescent material for EL device.

The result EL device (luminescence device) having an organic layercontaining the metal coordination compound of formula (1) exhibitsexcellent characteristics including a high efficiency luminescence, ahigh luminance for a long period, and a decreased luminescencedeterioration in energized state.

EXAMPLES II-1–II-15

In these examples, metal coordination compounds of formula (1) (Ex.Comp. Nos. (II-10), (II-15), (II-17), (II-21), (II-39), (II-43),(II-46), (II-85), (II-96), (II-122), (II-131), (II-146), (II-163),(II-177) and (II-182) were used in respective luminescence layers forExamples II-1–II-15, respectively.

Each of luminescence devices having a structure shown in FIG. 1B wereprepared in the following manner.

On a glass substrate (transparent substrate 15), a 100 nm-thick film(transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP: metalcoordination compound of formula (2) (95:5 by weight)

Organic layer 3 (electron transport layer 16) (30 nm): Alq3

Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

Metal electrode layer 2 (metal electrode 11) (100 nm): Al

Each of the thus-prepared luminescence devices was taken out of thevacuum chamber and was subjected to a continuous energization test in anatmosphere of dry nitrogen gas stream so as to remove devicedeterioration factors, such as oxygen and moisture (water content).

The continuous energization test was performed by continuously applyinga voltage at a constant current density of 70 mA/cm² to the luminescencedevice having the ITO (transparent) electrode (as an anode) and the Al(metal) electrode (as a cathode), followed by measurement of luminance(brightness) with time so as to determine a time (luminance half-life)required for decreasing an initial luminance (60–220 cd/m²) to ½thereof.

The results are shown in Table 19 appearing hereinafter.

COMPARATIVE EXAMPLE II-1

A comparative luminescence device was prepared and evaluated in the samemanner as in Example II-1–II-15 except that the metal coordinationcompound of formula (2) was changed to Ir-phenylpyridine complex(Ir(ppy)₃) shown below.

The results are shown in Table 19 below.

TABLE 19 Luminance Ex. Comp. No. half-life (Hr) Ex. No. II-1 (II-10) 750II-2 (II-15) 950 II-3 (II-17) 800 II-4 (II-21) 850 II-5 (II-39) 900 II-6(II-43) 750 II-7 (II-46) 900 II-8 (II-85) 500 II-9 (II-96) 650 II-10(II-122) 650 II-11 (II-131) 600 II-12 (II-146) 550 II-13 (II-163) 600II-14 (II-177) 450 II-15 (II-182) 450 Comp. Ex. II-1 Ir(ppy)₃ 350

As is apparent from Table 19, compared with the conventionalluminescence device using Ir(ppy)₃, the luminescence devices using themetal coordination compounds of formula (2) according to the presentinvention provide longer luminance half-lifes, thus resulting in an ELdevice having a high durability (luminance stability) based on a goodstability of the metal coordination compound of formula (2) of thepresent invention.

EXAMPLES II-16–II-17

In these examples, metal coordination compounds of formula (2) (Ex.Comp. Nos. II-15 and II-17 were used in respective luminescence layersfor Examples II-16–II-17, respectively.

Each of luminescence devices having a structure shown in FIG. 1C wereprepared in the following manner.

On a glass substrate (transparent substrate 15), a 100 nm-thick film(transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP: metalcoordination compound of formula (2) (93:7 by weight)

Organic layer 3 (exciton diffusion prevention layer 17) (10 nm): BCP

Organic layer 4 (electron transport layer 16) (30 nm): Alq3

Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

Metal electrode layer 2 (metal electrode 11) (100 nm): Al

Separately, each of the metal coordination compounds of formula (2) (Ex.Comp. Nos. (II-15 and (II-17))) for the thus-prepared luminescencedevices was subjected to measurement of photoluminescence spectrum inorder to evaluate a luminescent characteristic of the metal coordinationcompounds of formula (2) (Ex. Comp. Nos. (II-15) and (II-17)).Specifically, each of the metal coordination compounds was dissolved intoluene at a concentration of 10⁻⁴ mol/l and subjected to measurement ofphotoluminescence spectrum at 25° C. by using excited light (ca. 350 nm)and a spectrophoto-fluorometer (“Model F4500”, mfd. by Hitachi K.K.).

The results are shown in Table 20 appearing hereinafter.

The values of photoluminescence spectrum of the metal coordinationcompounds (Ex. Comp. Nos. (II-15) and (II-17)) were substantiallyequivalent to those in the luminescence devices under voltageapplication as shown in Table 20, whereby it was confirmed thatluminescence caused by the luminescence device was based on luminescenceof the metal coordination compound used.

EL characteristics of the luminescence devices using the metalcoordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and(I-49)) were measured by using a microammeter (“Model 4140B”, mfd. byHewlett-Packard Co.) for a current density under application of avoltage of 12 volts (current-voltage characteristic), using aspectrophotofluoro-meter (“Model SR1”, mfd. by Topcon K.K.) for a peakemission wavelength λ_(PE) (luminescence spectrum), and using aluminance meter (“Model BM7”, mfd. by Topcon K.K.) for a luminescenceefficiency (luminescence luminance). Further, an energy conversionefficiency was obtained according to the following equation:

$\text{Energy~~conversion~~efficiency~~(lm/W)} = {\frac{( {\pi \times \text{luminescence efficiency~~(cd/A)}} )}{\text{applied~~voltage~~(V)}}.}$

All the above-prepared luminescence devices showed a good rectificationcharacteristic.

The results are shown in Table 20.

Comparative Example II-2

A comparative luminescence device was prepared and evaluated in the samemanner as in Example II-16–II-17 except that the metal coordinationcompound of formula (1) was changed to Ir-phenylpyridine complex(Ir(ppy)₃) shown below.

The results are shown in Table 20 below.

TABLE 20 λ PE in toluene λ PE Energy conversion Luminescence Currentdensity Luminance Ex. No Ex. Comp. No. (nm) (nm) efficiency (lm/W)efficiency (cd/A) (mA/cm² at 12 V) half-life (Hr) II-16 (II-15) 524 5650.9 7.5 70 250 II-17 (II-17) 554 565 3.4 9.6 180 300 Comp. Ex. II-2Ir(ppy)₃ 510 510 6.0 19.0 20 150

As shown in Table 20, compared with the luminescence device usingIr(ppy)₃ (Comparative Example II-2) showing λ_(PE)=510 nm, theluminescence devices using the metal coordination compound of formula(2) according to the present invention showed longer peak emissionwavelengths (λ_(PE)=565 nm) by 55 nm, thus resulting in smaller relativeluminous efficiencies.

Smaller energy conversion efficiencies (0.9–3.4 lm/W) and luminescenceefficiencies (7.5–9.6 cd/A) of the luminescence devices of the presentinvention compared with those (6.0 lm/W and 19.0 cd/A) of theluminescence device using Ir(ppy)₃ may be attributable to the smallerrelative luminous efficiencies due to the longer peak emissionwavelengths, thus not resulting in essentially inferior luminescentcharacteristics of the luminescence devices using the metal coordinationcompound of formula (2) of the present invention.

As apparent from the results of the luminance half-lifes of theluminescence devices, compared with the luminescence device usingIr(ppy)₃ showing the luminance half-life of 150 hours, the luminescencedevices using the metal coordination compounds of formula (2) accordingto the present invention showed considerably longer luminance half-lifesof 250–300 hours.

EXAMPLE II-18 Synthesis of Ex. Comp. No. (II-15)

In a 5 liter-three necked flask, 169.5 g (1.28 M) of1,2,3,4-tetrahydronaphthalene and 3 liters of acetic acid were placedand stirred at room temperature. Under stirring, to the mixture, 650 g(1.67 M) of benzyltrimethylammonium bromide and 244.8 g (1.80 M) of zincchloride were successively added, followed by stirring for 5.5 hours at70° C. After the reaction, the reaction mixture was cooled to roomtemperature and poured into 3 liters of ice water, followed byextraction with methyl t-butyl ether. The organic layer was successivelywashed with 5%-NaHSO₃ aqueous solution, 5%-NaOH aqueous solution anddistilled water, followed by distilling-off of the solvent under reducedpressure to obtain 243.2 g of a dark brown liquid. The liquid wassubjected to vacuum distillation (distillation under reduced pressure)(boiling point=108–110° C. at 667 Pa) to obtain 130.2 g of6-bromo-1,2,3,4-tetrahydronaphthalene (Yield: 48.1%).

In a 5 liter-three necked flask, 67.55 g of6-bromo-1,2,3,4-tetrahydronaphthalene and 1480 ml of dry tetrahydrofuran(THF) were placed and cooled to −70 to −68° C. on a dry ice-acetone bathin a dry nitrogen gas atmosphere. At that temperature, to the mixture,200 ml of 1.6 M-butyllithium solution in hexane was added dropwise,followed by stirring for 2 hours at −67° C. or below. To borate in 435ml of dry THF was added dropwise at −70 to −68° C., followed by stirringfor 2 hours at −67° C. or below. The reaction mixture was graduallywarmed to room temperature and left standing overnight. The resultantreaction mixture was gradually added dropwise to a mixture of 108 ml ofHCl and 438 ml of water kept at 10° C. or below, followed by stirringfor 1 hour at that temperature. Thereafter, the mixture was subjected toextraction with toluene. The organic layer was washed with water,followed by distilling-off of the solvent under reduced pressure toobtain a residue. The residue was purified by silica gel columnchromatography (eluent: toluene/ethyl acetate=2/1) and recrystallizedfrom hexane to obtain 30.4 g of 1,2,3,4-tetrahydronaphthalene-6-boronicacid (Yield: 54.0%).

In a 1 liter-three necked flask, 17.8 g (114 mM) of 2-bromopyridine,20.0 g (127 mM) of 1,2,3,4-tetrahydronaphthalene-6-bronic acid, 160 mlof toluene, 80 ml of ethanol and 160 ml of 2M-sodium carbonate aqueoussolution were placed and stirred in a nitrogen gas stream at roomtemperature. Under stirring, to the mixture, 4.05 g (3.5 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by heat-refluxingfor 7 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene, and distilling off of thesolvent under reduced pressure to obtain a residue. The residue waspurified by silica gel column chromatography (eluent:toluene/hexane=2/1) to obtain 9.2 g of6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene (yellow liquid) (Yield:38.6%).

In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.30 g (6.21 mM) of6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene and 0.50 g (1.02 mM) ofIridium (III) acetylacetonate were added, followed by heat-refluxing for5 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 100 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by washing withacetone and purification by silica gel column chromatography (eluent:chloroform) to obtain 0.14 g of Iridium (III)tris[6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene] (orange powder)(Yield: 16.8%).

EXAMPLE II-19 Synthesis of Ex. Comp. No. (II-17)

In a 200 ml-four necked flask, 5.16 g (28.4 mM) of2-chloro-5-trifluoromethyl, 5.00 g (28.4 mM) of1,2,3,4-tetrahydronaphthalene-6-bronic acid, 25 ml of toluene, 12.5 mlof ethanol and 25 ml of 2M-sodium carbonate aqueous solution were placedand stirred in a nitrogen gas stream at room temperature. Understirring, to the mixture, 1.02 g (0.88 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by heat-refluxingfor 3.25 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene, and distilling off of thesolvent under reduced pressure to obtain a residue. The residue waspurified by silica gel column chromatography (eluent:toluene/hexane=1/1) and alumina column chromatography (eluent: toluene)and recrystallized from methanol to obtain 3.14 g of6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene(colorless crystal) (Yield: 39.9%).

In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130–140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.72 g (6.20 mM) of6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene and0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followedby heat-refluxing for 7 hours under stirring in nitrogen gas stream.

After the reaction, the reaction mixture was cooled to room temperatureand poured into 100 ml of 1N-HCl. The resultant precipitate wasrecovered by filtration and washed with water, followed by washing withacetone and purification by silica gel column chromatography (eluent:chloroform) to obtain 0.11 g of Iridium (III)tris[6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene](orange powder) (Yield: 10.5%).

As described hereinabove, the metal coordination compound of formula (2)according to the present invention provides a higher phosphorescenceefficiency and a shorter phosphorescence life and allows control of itsemission wavelength by appropriately modifying the alkylene group Yand/or substituents X1 and X2, thus being suitable as a luminescentmaterial for EL device.

The result EL device (luminescence device) having an organic layercontaining the metal coordination compound of formula (2) exhibitsexcellent characteristics including a high efficiency luminescence, ahigh luminance for a long period, and a decreased luminescencedeterioration in energized state.

1. A metal coordination compound, which can be used in a luminescentdevice, represented by the following formula (2):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene grouphaving 2–4 carbon atoms in which said alkylene group one or at least twonon-neighboring methylene groups can be replaced with —O—, —S— or —C(O)—and capable of including a hydrogen atom which can be replaced with alinear or branched alkyl group having 1–10 carbon atoms; and X₁ and X₂independently denote a hydrogen atom; halogen atom; a nitro group; atrialkylsilyl group having 1–8 carbon atoms; or a linear or branchedalkyl group having 1–20 carbon atoms in which said alkyl group one or atleast two non-neighboring methylene groups can be replaced with —O—,—S—, —C(O)—, —C(O)—O—, —O—C(O)—, —CH═CH— or —C≡C— and capable ofincluding a hydrogen atom which can be replaced with a fluorine atom. 2.The compound according to claim 1, wherein at least one of X₁ and X₂ isa hydrogen atom.
 3. A luminescence device, comprising an organiccompound layer comprising a metal coordination compound represented bythe formula (2) in claim
 1. 4. The device according to claim 3, whereinat least one of X₁ and X₂ is a hydrogen atom.
 5. The device according toclaim 3, further comprising a pair of electrodes oppositely disposed tosandwich the organic compound layer, wherein a voltage is appliedbetween the pair of electrodes to cause luminescence.